Method and apparatus for forming a structural member by deforming a grooved portion of a metal strip



Apnl 22, 1958 T. COLLINS 2,831,521

METHOD AND APPARATUS FOR FORMING A STRUCTURAL MEMBER BY DEFORMING A GROOVED PORTION OF A METAL. STRIP Original Filed Sept. 9, 1949 3 Sheets-Sheet 1 26 fi 5 @P 32 3e s3 A I INVENTOR TAPPAN COLLINS l3 s 2 ATTORNEY April 22, 1958 T. COLLINS 2,831,521

METHOD AND APPARATUS FOR FORMING A STRUCTURAL MEMBER BY DEFORMING A GROOVED PORTION OF A METAL STRIP Original Filed Sept. 9, 1949 5 Sheets-Sheet 2 N I N l I o I o N g m 3 N m 0) Q n N l II s: Q

TO N

I] N m INVENTOR m TAPPAN COLLINS N ATTORNEY P 22, 1958 T. COLLINS 2,831,521

METHOD AND APPARATUS FOR FORMING A STRUCTURAL MEMBER BY DEFORMING A GROOVED PORTION OF A METAL STRIP Original Filed Sept. 9, 1949 5 Sheets-Sheet 3 INVENIOR TAPPAN COLLINS BY ATTORNEY METHOD AND APPARATUS FOR FORMING A STRUCTURAL MEMBER BY DEFORMING A GRGOVED PURTION F A METAL STRIP Tappan Coiiins, Grosse Pointe Woods, Mich., assignor to National Steel Corporation, a corporation of Delaware Original application September 9, 1949, Serial No. 114,882, now Patent No. 2,735,520, dated February 21, 1956. Divided and this application March 31, 1953, Serial No. 348,691

14 Claims. (Cl. 153-13 The present invention relates to a novel apparatus for and a method of forming structural members from strip metal and particularly relates to an improved apparatus for and a method of forming a structural member adapted to receive and hold nails from strip metal, such as strip steel.

This application is a division of copending application Serial No. 114,882 filed September 9, 1949, for Structural Member and Method of Forming the Same Elongated nailable structural members have been proposed that include a longitudinal groove. The groove includes a nail bending recess that is substantially circular in cross sectionand a restricted entering throat opening into the recess. A relatively small diameter mandrel extends the length of the recess so that when a nail is driven into the groove, the pointed, leading end of the nail passes through the throat into the recess and bends around the mandrel and the nail is held in place by this end which is hooked around the wire. Nailable structural members of this type have relatively little resistance to being wedged open. When a nail is driven into the groove, the nail tends to wedge open the groove over a relatively long length as there is nothing which localizes the forces exerted by the nail. As a result, the nailable member is only practical in heavy hot rolled sections and insofar as is known, members of this type are not being used.

in the copending application Serial No. 114,882, issued February 21, 1956, as Patent No. 2,735,520, there is disclosed a novel nailable structural member of the above class in which the longitudinal groove is displaced laterally of its longitudinal axis. With such an arrangement the walls of the nailing groove'are strengthened against spreading and the forces exerted by a nail driven into the groove are localized, while the overall strength of the member is increased allowing the member to be formed from relatively light gauge strip material. In the preferred embodiment, successive lengths of the 1ongitudinal groove are alternately displaced in opposite lateral directions from its original axis so that the 1ongitudinal axis of the groove is in the shape of a sinusoidal curve.

The present invention discloses a novel method of and apparatus for fabricating a structural member of the character disclosed in the copending application.

It is therefore an object of this invention to provide an improved method of and apparatus for fabricating'an elongated structural member containing a longitudinally grooved portion that is relatively strong and that can be formed from relatively thin strip material.

It is another object of the present invention to provide apparatus for and method of forming a nailable structural member that includes a nail receiving groove of the type in which the nail is bent around a mandrel in the groove, and in which the nailable structural member can be fabricated from relatively light strip metal, in which the nailable member is so co'nstructed'ahd'ar- .tates Pato o IF 2,831,521 Patented Apr. 22, 1958 ICC ranged as to localize the forces exerted by a driven nail tending to spread apart the nailing groove walls, and in which nailable member the walls of the nail receiving and bending groove strengthen the member.

In accordance with the present invention, and after a groove having a straight longitudinal axis has been formed in the stripmetal, the walls defining the groove are stretched and elongated so that the groove defining portion of the strip is longer than the main body of the strip. The longitudinal axis then assumes the form of a wavy line instead of a straight line. Preferably, suecessive lengths of the elongated groove are alternately displaced in opposite lateral directions from the original axis so that the longitudinal axis of the groove assumes the shape of a sinusoidal curve. The walls of the nailing groove are strengthened against spreading and the forces exerted by a nail driven into the groove are 10- calized. In addition, the curved grooved portion strengthens the member, and the member may be formed from relatively light or thin sheet metal, such as strip steel.

These and other objects and advantages will become I more apparent from the following description, taken with the accompanying drawings, in which:

Figure 1 is a side view diagramatically illustrating one form of apparatus embodying the principles of the present invention for producing my novel structural member;

Figure 2 is an isometric view of a paratus of Figure 1;

Figure 3 is a plan view of the apparatus of Figure 1;

Figures 4, 5 and 6 aresectional views taken along line 4-4 of Figure 3 and illustrating different steps in the shaping of the grooved portion;

Figure 7 is an enlarged fragmentary sectional view showing a nail in place; and

Figures 8 to 11, inclusive, are isometric views illustrating various shapes of structural members that may be fabricated by practicing the principles of the present invention.

Referring to the drawings and more particularly to Figures 1 to 7, inclusive, the apparatus diagrammatically shown is for forming a nailable member from an elongated strip or sheet S which includes a longitudinal midportion 10 defining an open longitudinal groove 11. The mid-portion 10 integrally joins the spaced, coplanar side portions 12 and 13 so that the elongated strip S consists of a longitudinal mid-portion Ill which is laterally displaced from the plane of the strip and which defines a groove 11 and a coplanar longitudinal side portion integrally joined to each lateral edge of the mid-portion 10. The groove 11 may be formed by any suitable means and in any suitable manner.

The apparatus for shaping the strip S includes a stretcher roll 15 and two tensioning means 16 and 17 arranged so that the strip S passes through an are about a portion of the periphery of the stretcher roll 15. The tensioning or drag means 16 includes a pair of rolls 19 and 20 rotatably mounted on shafts 21 and 22, respectively, and-adapted to engage the opposite surfaces of the strip S. Any suitable means, such as a brake or generator (not shown), may be connected to shafts 21 and 22 to apply drag to the rolls 19 and 20 so that the rolls 19 and 20 resist movement of the strip toward the stretcher roll 15. The tensioningor pull means 17 also includes a pair of power actuated rolls 23 and 24 rotatably mounted on shafts 25 and 26.. Each of the rolls 2th and 24 may be of the split-type as illustrated to provide an interportion of the apmediate opening into which the longitudinal groove may 3 the rolls for pulling the strip S. Tensioning means of various types are well known and are customarily used around steel mills for moving strip under tension along a path. With the pull means 17 pulling the strip S with sufficient force to move it past the drag means 16 and the stretcher means 15, the strip S is moved in the directionindicated by arrows under heavy tension.

The stretcher means or roll 15 includes a mid-portion roll 28 of relatively large diameter that fits into or engages the groove 11 of the grooved mid-portion 19 of the strip S. Shoulder portions 29 and 30 extend laterally from the sides of the mid-portion for engaging the surfaces of the corresponding side portions 13 and 12. With this arrangement, the strip S is continuously moved through an are about the stretcher roll 15. As the groove fitting mid-portion 28 has a radius larger than the shoulders 29 and 30 by a distance equal to the depth of groove 11, the groove defining mid-portion of the strip extends outwardly from side portions 12 and 13 and the mid-portion 10 moves through an arc of greater radius and a longer path than the side portions 12 and 13. The side portions 12 and 13 are under tension so that they can not buckle, and the bending of the strip S about the stretcher roll under tension stretches the groove defining midportion 10 with the peak 32 being stretched the most. It will be noted that the tensioning rolls do not directly grip the grooved mid-portion 10.

When the strip S with the stretched or elongated midportion 10 passes the stretcher means, the strip moves along a straight path toward the drag rolls 23 and 24. When the strip S is straightened after the groove-defining portion 10 has been stretched, the portion 10 buckles as it is longer than portions 12 and 13. The portion when it buckles assumes a wavy shape with successive lengths laterally displaced in alternately opposite directions. The rib or groove defining portion assumes a wavy shape, that is, the longitudinal axis instead of being a straight line as it is originally becomes a wavy or irregular line because it has been elongated. This waviness or lateral displacement increases the strength of the grooved portion. Preferably, this waviness is controlled so as to provide the maximum increase in strength by positively laterally displacing successive equal lengths in alternately opposite directions so that the longitudinal axis of the groove assumes a sinusoidal curve.

Between the stretcher roll and the pull tension means 17, there is means 35 for laterally displacing successive equal lengths of the lengthened grooved portion 10 in alternately opposite directions. A rotatable eccentric roll 36 is mounted on a shaft 37 which is normal to the portion 12. Similarly, an eccentric roll 38 'is mounted on shaft 39. Both rolls 36 and 38 are arranged to engage therebetween the opposite sides of the grooved portion 10. The rolls 36 and 38 are proportioned and arranged so that the distance between their closest points 40 and 41 remains substantially constant and the sum of their radii between their axes is substantially constant. With this arrangement and upon movement of strip S between and past the rotating rolls 36 and 38, the space between the rolls moves back and forth equal distances from a point midway between the centers of the rolls and the metal is moved back and forth laterally. In other words, the rolls control the lateral displacement of portion 10 so that successive equal lengths are displaced in alternately opposite directions. As shown in Figure 3, portion 42 is displaced to the left, portion 43 is displaced to the right, and portion 44 is displaced to the left. These portions are of equal length. Without the rolls 36 and 38, the grooved portion would be wavy or corrugated but the waves or corrugations would not be uniform with the result that the resistance to spreading would not be uniformly increased along the length of the strip.

When passing around the stretcher roll, the groove 11 is wide open and the sides 46 and 47 are either parallel or flared outwardly so that the entrance 48 defined by the shoulders 49'and 50 is as wide or wider than any other portion of the groove 11 to permit entrance of the larger roll 28. After the grooved portion has been stretched and elongated, the shoulders 49 and 50 must be brought towards each other to restrict the throat 48. Preferably, but not necessarily, this is done when the elongated portion is laterally displaced. As shown more particularly in Figures 4 to 6, on the lower ends of each of shafts 37 and 39 there is mounted a roll 52 and 53, respectively. Rolls 52 and 53 are rotatable independently of rolls 36 and 38 as the rolls do not rotate at the same angular velocity. The angular velocity of rolls 52 and 53 is constant, whereas the angular velocity of rolls 36 and 38 varies. Thus, of each pair of rolls 36 and 52 or 38 and 53, at least one roll is rotatable independently of the corresponding shaft, and the two rolls are supported for rotation independently of each other. Separate shafts may be provided for the rolls of each pair of rolls.

The squeeze rolls 52 and 53 squeeze the shoulders inwardly toward each other to reduce the throat 48 to a relatively narrow width that is approximately the same width as the diameter of the nail to be driven into the grove. Squeezing the shoulders together causes the remaining portion of the groove 11 to assume a substantially circular shape and define a slot or recess 55 that is circular or rounded in cross-section. In Figure 4, the parts are shown in the position assumed when the grooved portion is centrally positioned, and in Figures 5 and 6 the parts are shown in the positions assumed when the grooved portion is displaced to the left and when the grooved portion is displaced to the right, respectively. It will be noted that after the grooved portion has been shaped, the grove 11 includes a substantially circular slot or recess 55 and a restricted entry throat 48.

A mandrel or wire 56 is provided in the slot 55. This mandrel 56 may be inserted at any itme, preferably before the shoulders are squeezed together. The groove engaging roll 28 contains a slot 57 extending about its periphery and the wire 56 fits this slot. The strip S and wire 56 are simultaneously fed past the stretcher roll 15 so that the wire is in place when the rolls 52 and 53 reduce the throat 48. The wire 56 floats in the slot 55. While stretching and lateral displacement of the grooved portion 10 tends to cause the grooved portion to grip the wire at spaced points along its length, the wire floats and will assume a central position in the slot when a nail is driven into the Slot. The diameter of wire 56 is smaller than the diameter of the slot 55, and the difference in these diameters, preferably, is substantially equal to the width of throat 48 and substantially equal to the diameter of the nail driven into the slot so that the wire and slot together define a reentrant nail receivrng groove.

In accordance with the present method of forming a structural member from an elongated strip S having a longitudinal grooved mid-portion 10 joining coplanar opposite edge portions 12 and 13, the mid-portion 10 is elongated relative to the edge portions. Preferably, the elongating of mid-portion 10 is eflected by passing the grooved strip through an arcuate path while under tension and with the grooved portion extending outwardly so that the grooved portion 10 passes through the longer path. Then successive lengths of the lengthened midportion are laterally displaced in alternately opposite directions. The shoulders 49 and 50 are squeezed together and a wire 56 is placed in the groove before or after the shoulders are squeezed together.

Referring to Figure 7, the resulting elongated nailable structural member 58 is adapted to receive and hold nails, for fastening thereto other members, such as a board 59. When a nail 60 is driven through the board, the leading end portion 61 of the nail after passing "through the board and through the entering throat 48 enters the slot 55. The wire 56 centers in the slot 55 and the leading end of the nail then passes through the reentrant groove 62 defined by the opposed spaced surfaces of the wire and the wall of slot 55. As the leading end portion 61 of the nail passes through groove 62, it is bent around the wire 56 so that the nail is held in place. The forces required to bend the nail tend to deform the walls of the groove and tend to spread apart the shoulders 49 and 50. Spreading apart of the shoulders 49 and 50 would weaken the structure, and if these shoulders are spread very much, the nail holding properties are lost. Stretching and laterally displacing the walls of the nailing groove strengthens the member against spreading of the walls and increases the loading capacity of the entire member.

When the grooved portion is stretched the peak 32 of the grooved portion is lengthened or stretched the most while the shoulders 49 and 50 are stretched the least. The throat or slot 48 which extends the length of the strip will be substantially straight while the peak 32 will have the greatest lateral curvature. The longitudinal axis of the nailing groove will curve back and forth somewhat less than the peak 32.

The present method of elongating the grooved poring longitudinally of theweb of the U-shaped member.

Figure 11 illustrates a composite structural member 90 made up of a U-shaped member 91 and two similar L- shaped members 92 and 93. The U-shaped member 91 includes a web portion 94 with lateral flanges 95 and 96 along each side. Each lateral flange 95 and 96 includes a grooved portion 97. Each L-shaped member 92 and 93 includes a leg 99 and a leg 100. Each leg 100 includes grooved portion 101. The legs 99 are joined to web 94 by spot welds or other suitable means to form a generally H -shaped member.

. In each of Figures 9 to 11, the one or more grooved portions defining a nailing groove is formed as described with reference to Figures 1 to 7. When producing the tion relative to the coplanar side portions has been shown and described for nailing grooves of the type which include a substantially circular nail receiving slot and a restricted throat opening into the slot. The present invention is not limited to this exact shape or nail receiving slots which include a mandrel. I

The strip S after being formed into a nail receiving member may be used without further modification as shown in Figure 7. The nailable member 58 may be additionally modified or may be combined with other members to form the desired type of structural members. Figures 8 to 11 illustrate other shapes also embodying the principles of the present invention. Each of these shapes is formed in accordance to the previously described method, that is, a strip including coplanar side portions joined by a grooved mid-portion has the grooved mid-portion elongated to produce a nailable structural member like that shown in Figure 7 in which the coplanar shoulders are the same width as or a different width than shoulders 12 and 13. The shoulders 12 and 13 may be subsequently bent or formed to the desired shape.

Referring more particularly to Figure 8, this elongated nailing member 65 includes a longitudinally grooved portion 66 formed as previously described with side portions 67 and 68. Each side portion 67 and 68 includes a lateral shoulder portion 69 extending along the corresponding side of the groove portion 66 and a web portion 70 extending laterally downwardly from the shoulder portion 69 and terminating in a flange 71 extending laterally outwardly. After the nailable member 65 has been formed with the flanges 67 and 68 coplanar, the flanges 67 and 68 are formed or bent to the shape shown.

Figure 9 illustrates a'nailable member 73 having two longitudinal nailing grooves 74 and 75 joined by a midportion 76. Coplanar side portions 77 and 78 extend along opposite sides of the member 73.

In Figure 10; there is shown a nailable member 79 that includes three nailing groove defining portions 80, 81 and 82. Grooved portions 81 and 82 are joined by an elongated web 84 and grooved portions 82 and 83 are joined by an elongated web 85. Lateral shoulders or flanges 86 and 87 extend along the outer sides of grooved portions 81 and 83., respectively. 7 The grooved portions were elongated while the side portions 86 and 87 and the webs 84 and 85. were coplanar. The webs 84 and 85 were then bent along lines 88 and 89, respectively, to form the generally U-shaped member 79 having a grooved portion adapted to receive and grip nails along each flange and at least one grooved portion 82 extendmembers 73, 79 and 91, a plurality of grooved portions are simultaneously stretched. When a grooved portion or portions is stretched, the strip is substantially coplanar with the webs or side portions all coplanar and only the grooved portion or portions is displaced laterally from the plane of the strip.

The present method is not limited to the present apparatus shown and described in detail. Guide meansother than roll 15 may be used for guiding the grooved strip through an arcuate path with grooved portion 10 extending outwardly from the side portions 12 and 13 relative to the axis of the arcuate path. Other types of tensioning means may be used for moving the strip past the stretcher means under tension.

The strip metal may be any suitable metal and may be, for example, hot or cold rolled strip. The strip, after formation of the nailing groove, may be heat treated and hardened. A high tensile low alloy steel may be used.

I claim:

1. In the method of forming a structural member from an elongated metal strip, the steps comprising, shaping a longitudinal mid-portion of the strip to define a longitudinal groove, the groove defining mid-portion being joined to opposite coplanar edge portions of the strip, elongating the groove defining mid-portion relative to the edge portions, 'and laterally displacing successive lengths of the elongated groove defining mid-portion in alternately opposite directions from the longitudinal axis of the groove.

2. In the method of forming a structural member from an elongated metal strip, the. steps comprising, shaping a longitudinal mid-portion of the strip to define a longitudinal groove, the groove defining mid-portion being joined to opposite coplanar edge portions of the strip, elongating the groove defining mid-portion relative to the edge portions, and laterally displacing successive lengths of the elongated groove defining mid-portion, the successive lengths being equal in length and being alternately displaced in opposite directions so that the longia tudinal axis of the groove assumes the form of a sinusoidal curve.

3. In the method of forming a structural member from an elongated metal strip having a laterally displaced longitudinal mid-portion forming a longitudinal groove in the strip, the steps comprising elongating the midportion relative to the edge portions, and laterally displacing successive lengths of the elongated mid-portion in alternately opposite directions from the longitudinal axis of the groove.

4. In the method of forming a structural member from an elongated metal strip having a laterally displaced longitudinal mid-portion forming a longitudinal groove in the strip, the steps comprising elongating the midportion relative to the edge portions, and laterally dis placing successive lengths of the elongated mid-portion defining the groove, the successive lengths being equal in length and being alternately displaced in opposite directions so that the longitudinal axis of the groove assumes theformof a sinusoidal curve.

5. In the method of forming a structural member from an elongated metal strip having a laterally displaced longitudinal mid-portion forming a longitudinal groove in the strip, the steps comprising passing the strip through an arcuate path about an axis parallel to the coplanar edge portions, the edge portions facing the axis and the longitudinal mid-portion extending outwardly away from the edge portions and the axis so that the mid-portion passes through a longer path than the edge portions, and maintaining the strip under tension while moving through the arcuate path and thereby elongating the mid-portion relative to the edge portions.

6. In the method of forming a structural member from an elongated metal strip having a laterally displaced longitudinal mid-portion forming a longitudinal groove in the strip, the steps comprising passing the strip through an arcuate path about an axis parallel to the coplanar edge portions, the edge portions facing the axis and the mid-portion extending outwardly away from the edge portions and the axis so that the midportion passes through a longer path than the edge portions, maintaining the strip under tension while moving through the arcuate path and thereby elongating the mid-portion relative to the edge portions, and passing the mid-portion between eccentric cam rolls rotatably mounted about axes normal to the coplanar edge portions, said eccentric rolls being constructed so that upon rotation the sum of their radii between the axes is substantially constant whereby the longitudinal axis of the groove assumes a sinusoidal shape.

7. In the method of forming a structural member from an elongated metal strip having a laterally displaced longitudinal mid-portion forming a longitudinal groove in the strip and coplanar longitudinal edge portions on opposite sides of the mid-portion, the midportion including side portions and shoulder portions joining the side portions to the coplanar edge portions of the strip, elongating the mid-portion relative to the edge portions of the strip, laterally displacing successive lengths of the elongated mid-portion in alternately opposite directions from the longitudinal axis of the groove, placing a wire in the groove and forcing the shoulder portions toward each other so that the shoulder portions define a relatively narrower entry throat to the groove of a width less than the thickness of the wire.

8. In the method of forming a nailable structural member from an elongated metal strip, the steps comprising forming a longitudinal groove in a longitudinal mid-portion of the strip having coplanar longitudinal edge portions on opposite sides of the groove, the mid- 1 portion including side portions and shoulder portions joining the side portions to the coplanar edge portions of the strip, laterally displacing successive lengths of the elongated mid-portion, successive lengths of the elongated mid-portion being equal in length and being alternately displaced in opposite directions so that the longitudinal axis of the groove assumes the form of a sinusoidal curve, placing a wire in the groove and forcing the shoulder portions toward each other so that the shoulder portions define a relatively narrower throat to the groove of a width less than the thickness of the wire.

9. in apparatus for progressively forming an elongated metal member from elongated metal strip including a longitudinally grooved mid-portion between longitudinal coplanar edge portions, the combination comprising, stretcher roll means including relatively smaller diameter side portions adapted to engage a surface of the strip coplanar edge portions and including a mid-portion of larger diameter adapted to fit into the grooved mid-portion of the strip, means to move the strip over the stretcher roll means to guide the strip through an arcuate path about the axis of the stretcher roll means with the grooved mid-portion extending outwardly so that the mid-portion passes through an arc of longer linear length than the edge portions, means for maintaining the strip under tension upon movement of the strip through said arcuate path including means ahead of the stretcher roll means for applying drag to the strip and means behind the stretcher roll means for pulling the strip so that the groove-forming mid-portion is stretched and lengthened relative to the edge portions, and means for straightening the strip material following its movement through the arcuate path.

10. In apparatus for progressively forming an elongated metal member from elongated metal strip including a longitudinally grooved mid-portion between longitudinal coplanar edge portions, the combination comprising, means for guiding the strip through an arcuate path about an axis with the grooved mid-portion extending outwardly so that the mid-portion passes through an arc of longer linear length than the edge portions, means for moving the strip past the strip guiding means through said arcuate path under tension including means ahead of the strip guiding means for applying drag to the strip and means behind the strip guiding means for pulling the strip so that the groove-forming mid-portion is stretched and lengthened relative to the edge portions, and means behind the strip guiding means adapted to engage the stretched mid-portion and displace successive lengths of the mid-portion in alternately opposite lateral directions.

ll. In apparatus for progressively forming an elongated metal member from elongated metal strip including a longitudinally grooved mid-portion between longitudinal coplanar edge portions, the combination comprising, means for guiding the strip through an arcuate path about an axis with the grooved mid-portion extending outwardly so that the mid-portion passes through an arc of longer linear length than the edge portions, means for moving the strip past the strip guiding means through said arcuate path under tension including means ahead of the strip guiding means for applying drag to the strip and means behind the strip guiding means for pulling the strip so that the groove-forming mid-portion is stretched and lengthened relative to the edge portions, and means hehind the strip guiding means adapted to engage the stretched mid-portion and displace successive lengths of the mid-portion in alternately opposite lateral directions, said displacing means including a pair of spaced rotating eccentric cam rolls rotating about axes normal to the coplanar edge portions, said eccentric rolls being constructed so that upon rotation the sum of their radii be tween the axes is substantially constant whereby the longitudinal axis of the groove assumes a sinusoidal curve.

12. In apparatus for progressively forming an elongated metal member from elongated metal strip including a longitudinally grooved mid-portion between longitudinal coplanar edge portions, the combination comprising, a stretcher roll including relatively smaller diameter side portions adapted to engage a surface of the strip side portions and including a mid-portion of larger diameter adapted to fit into the groove, means for moving the strip past the stretcher roll including drag roll means ahead of the stretcher roll adapted to engage the strip moving toward the stretcher roll and apply drag to the strip and pull roll means in back of the stretcher roll adapted to engage the strip moving away from the stretcher roll and pull the strip past the stretcher roll, the drag and pull roll means being positioned so that the strip moves through an are about the stretcher roll and the drag and pull roll means applying tension to the strip whereby the mid-portion is stretched and lengthened rela tive to the side portions, and means behind the stretcher roll adapted to engage the stretched mid-portion and displace successive lengths of the mid-portion in alternately opposite lateral directions.

13. In apparatus for progressively forming an elongated metal member from elongated metal strip including a longitudinally grooved mid-portion between longitudinal coplanar edge portions, the groove defining midportion including side portions and shoulder portions joining the side portions to the coplanar edge portions of the strip, a stretcher roll including relatively smaller diameter side portions adapted to engage a surface of the strip side portions and including a mid-portion of larger diameter adapted to fit into the groove, means for moving the strip past the stretcher roll including drag roll means ahead of the stretcher roll adapted to engage the strip moving toward the stretcher roll and apply drag to the strip and pull roll means in back of the stretcher roll adapted to engage the strip moving away from the stretcher roll and pull the strip past the stretcher roll, the drag and pull roll means being positioned relative to the stretcher roll so that the strip moves through an are about the stretcher roll and the drag and pull roll means applying tension to the strip whereby the mid-portion is stretched and lengthened relative to the side portions, means behind the stretcher roll adapted to engage the stretched mid-portion and displace successive lengths of the mid-portion in alternately opposite lateral directions,

said displacing means including a pair of spaced rotating eccentric cam rolls rotating about axes normal to the coplanar edge portions, said eccentric rolls being constructed so that upon rotation the sum of their radii between the axes is substantially constant whereby the longitudinal axis of the groove assumes a sinusoidal shape, and means for forcing the shoulder portions toward each other to define a relatively narrower groove throat.

14. The method of forming a structural member from an elongated metal strip, the elongated metal strip having a longitudinal groove in a longitudinal mid-portion of the strip and coplanar edge portions on opposite sides of the longitudinal groove, the steps comprising passing the strip through an arcuate path about an axis parallel to the coplanar edge portions to elongate the mid-portion relative to the edge portions and thereafter moving the strip along References Cited in the file of this patent UNITED STATES PATENTS 135,150 Pearce Jan. 21, 1873 338,059 Gocht Mar. 16, 1886 483,192 White Sept. 27, 1892 674,555 Harter May 21, 1901 1,005,848 Lane Oct. 17, 1911 1,339,104 Cooke May 4, 1920 1,376,497 Yoder May 3, 1921 1,793,351 Bell Feb. 17, 1931 1,954,414 Kalischer Apr. 10, 1934 1,971,723 ODell Aug. 28, 1934 2,165,282 Loggins July 11, 1939 2,251,967 Yoder Aug. 12, 1941 2,269,549 Oeckl Jan. ,13, 1942 2,281,299 Steenstrup Apr. 28, 1942 2,294,434 Wilson Sept. 1, 1942 2,326,470 Lermont Aug. 10, 1943 2,337,047 Hunter Dec. 21, 1943 2,432,828 Stone Dec. 16, 1947 2,457,147 Hall Dec. 28, 1948 2,464,169 Bentley Mar. 8, 1949 2,539,038 Shumaker Jan. 23, 1951 2,549,442 Fischer Apr. 17, 1951 2,600,442 Stanius June 17, 1952 2,630,890 Macomber Mar. 10, 1953 2,735,520 Collins Feb. 21, 1956 FOREIGN PATENTS 7,122 Switzerland May 27, 1893 889,029 France Sept. 20, 1943 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,831,521 April 22, 1958 Tappan Collins.

It is herebir certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 67, before "apparatus" insert a novel column 2, line 25, for "diagramatically" read diagrammatically column 5, line 3'7, for "accordance to" head we accordance with column 5, line 51', for 'groove" read grooved column 7, line 38, after the comma insert the steps comprising line 53, after the comma insert n elongating the groove defining mid-=portion relative to the remainder of the strip,

Signed and sealed this 30th day of December 1958.

(SEAL) Attest:

KARL H, AXLINE v I ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

